NEWER METHOD – USE OF GEL – CONTROLLING COCKROACHES
DR. DINESH CHANDRA

SENIOR SCIENTIST-CUM-EXTENSION ENTOMOLOGIST
I.A.R.I., NEW DELHI – 110 012

India is an agricultural base country. In the recent past moderanisation and urbanisation has attracted more and more population towards cities. It has caused denser population in the cities. Nowadays, all ladies are aware and concerned about their kitchen-mate, a asmall may be bigger six-legged brown coloured insect called cockroaches or roaches. Infact, "sewar" system has attributed much more in its fast-building of population. No doubt that these insects have come to earth several thousands years before. Thest tiny insects are not the native of our country but nowadays they are found in each corner and every services of the house, kitchen is the common place.

INTRODUCTION
Cockroaches, as they are found are of two types :- bigger ones, 4 cms and more are Periplanata americana (L) or American cockroaches, the smaller ones to 1 to 1.5 cm in size are called Blattella germanica (L) or German cockroaches. P americana may produce a capsule (containing 14 to 16 eggs) per week and may release as many as 100 capsules during their life span of over 1^1/2 years.

B. Germanica may produce lesser number of capsules containing 25-30 eggs 9almost double the number as that of bigger cockroaches) and may release 1-7 or more capsules during their life span of 2-5 months.

Material & Methods : The trials were conducted at 13 locations in the Delhi city on two different surfaces. Later founding the encouraging results, it was tried at 32 locations on varioud surfaces. In second phase it was retested at 8 sites although roaches were left in neligible number.

Surfaces tried – 1. Cement floor 2. Marbel stabs 3. Cement stabs 4. Sunmica board 5. Wooden slabs 6. Ceramic tiles 7. Ceramic wash basin (all around outside and base) and 8. Paper (underside) being used to spread in cupboards of kitchen and stores.

Material used ‘a gel’ known as Pestrin was supplied by M/s. Hughes & Hughes Chem Ltd., as a free sample.

Two trials were carried out. Firstly, it was tested only on cement floor & wooden slabs, at 13 locations comprising kitchen and cupboards of departmental stores of Delhi.

Second trial was also conducted in Delhi at 8 surfaces including the two in first case and at 32 locations including 8 sites screened earlier.

The gel – ‘PESTRIN’ was applied only once with the help of flat hard brush almost uniformly.

Observations

Surfaces	Cement Floor	Marble Slabs	Cement Slabs	Sunmica board	Wooden board	Ceramic tiles	Ceramic wash basin
I. No. of Locations	8				5
II No. of Locations	*5+1	6	7	2	*3+1	1	4

* Locations of first trial were repeated

Results & Discussions
It was a general feeling the P. americana was more confined to ground floors and nearer to either water source or manholes, precisely around wet area, whereas B. germanica was more near dried and compact sites like stores, behind electrical switches & boards, inside the grills, wasters sandwitch makers, mixibase, botton of not plates, handles of pressure cookers and beneath the papers spread in cupboards and so on.

During the trial, it was observed that P. americana was found dead, the very next day after applying ‘gel’ at surface No. 7 and on the other day at 3 more surfaces Nos. 5,6,8. These insects were found dead or drying even after six days, although the dead ones were removed every morning without disturbing the gel. Surfaces Nos. 2x4 were not found suitable to attract P. americana.

B. germanica was observed dying from the day 1 at all surfaces except No. 7 situation was almost similar at all locations. Rate of morality was higher on the 3^rd day and within a week’s time all of them were either dead or lying immobile. None could be observed alive. However, on 9^th day a few more (newly hatched or emerged) were seen, which too were found dead the other day. Surface No. 7 does attract more P.americana, whereas, surfaces Nos. 3, 5, 8 and 1 proved to be more compatible with this gel (these are described in decreasing order of compatibility).

Summary
Based on the experiments conducted on 8 different surfaces at various locations it could be ascertained that the ‘gel’ known as "PESTRIN" is undoubtedly very effective again these brown coloured insects under Delhi conditions. Their toxicity persistance is also satisfactory than required. It remains effective and the toxicity persists than for many more days while, cockroaches vanishes from the site.

BIO-DATA
Dr. Dinesh Chandra, M.Sc (Zool. Expl. In Entomology) Lucknow University, Ph.D. (Zool Ent.) University of Bihar; Born 26 July 1940. Present position – Senior Scientist-cum-Extension Entomologist at IARI, New Delhi since 1966. Engaged in Research, teaching & extension. Field of specialization-Pest Control, pesticide, application technology, rodent control and so on. Profession experience 34 years. Publ. Over 50 papers including popular articles and books. Fellow-Nehru Experimental Centre, Member Production Unit of IARI, Green Cross Medical Soc. India, Pest Control Association of India.